Launderable plant-based substrate that is thermally bonded with biobased fibers

ABSTRACT

Described herein are nonwoven fabrics, wipers, and methods of making thereof. According to one or more aspects, a nonwoven fabric includes an entangled web of individualized bast fibers and polylactic acid (PLA) fibers. At least a portion of the bast fibers and a portion of the PLA fibers are thermally bonded together.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a U.S. national stage of application under 35 U.S.C. § 371 of PCT/US2018/035523, filed on Jun. 1, 2018, which claims priority to U.S. Provisional Patent Application No. 62/520,511, filed on Jun. 15, 2017, both of which are incorporated by reference herein in their entirety.

TECHNICAL FIELD

Aspects of the present invention are directed generally to nonwovens. More specifically, aspects of the present invention are related to biobased nonwovens.

BACKGROUND OF THE INVENTION

The term “biobased product” was defined by the United States Department of Agriculture (USDA) Secretary in the Farm Security and Rural Investment Act of 2002 as a commercial or industrial product (other than food or feed) that is composed, in whole or in significant part, of biological products, renewable domestic agricultural materials (including plant, animal, and marine materials), forestry materials, or an intermediate feedstock. Examples of agricultural resources that make up many biobased products include, for example, soybeans, corn, kenaf, flax, jute, and numerous other types of crops.

Natural bast fibers are biobased fibers found in the stalks of the flax, hemp, jute, ramie, nettle, Spanish broom, and kenaf plants, to name only a few. Typically, native state bast fibers are 1 to 4 meters in length. These long native state fibers are comprised of bundles of individual fibers which are straight and have a length between 20 and 100 mm. The bundled individual fibers are glued together by a class of plant resins called pectins.

Bast fibers can be used to create a variety of products, including nonwoven substrates and wet and dry wipers. To prove that nonwovens and wipers will sufficiently biodegrade, they can be tested against various standards, such as ASTM International D6400 and/or D6868 test standards, and/or certifications, such as the Biodegradable Products Institute® (BPI®) certification. Brawny Industrial® FLAX Cloths (Georgia-Pacific Consumer Products LP, Atlanta, Ga.) are examples of flax-based wipers that are certified by the BPI® to be a BPI® Compostable Product, as well as to meet the ASTM International D6400 and/or D6868 test standards.

Various methods can be used to form biobased wipers from natural fibers. Although hydroentangled wipers are strong and absorbent, they may not withstand mechanical laudering and therefore may not be suitable for reuse. While hydroentangled fibers create strong bonds between the fibers, which provide strength to the substrates, the bonds may still be weakened by mechanical agitation in water, for example in laundry and dishwashing machines used to clean the nonwovens.

Therefore, there is a need for methods to form a stronger, biobased nonwoven substrate and/or wiper that can withstand mechanical agitation, during for example, washing/laundering, while still maintaining the USDA biobased certification. It is to solving this problem that aspects of the present invention are directed.

SUMMARY OF THE INVENTION

Aspects of the present invention are directed to nonwoven fabrics, wipers, and methods of making thereof. According to one or more aspects, a nonwoven fabric includes an entangled web of individualized bast fibers and polylactic acid (PLA) fibers. At least a portion of the bast fibers and a portion of the PLA fibers are thermally bonded together.

According to one or more aspects, a nonwoven fabric includes an entangled web of individualized bast fibers, polylactic acid (PLA) fibers, and cellulose fibers. At least a portion of the PLA fibers are thermally bonded to the bast fibers and at least a portion of the PLA fibers are thermally bonded to the cellulose fibers.

Yet, according to other aspects, a method of making a nonwoven fabric includes forming a web of individualized bast fibers and polylactic acid (PLA) fibers. The method further includes entangling the individualized bast fibers and the PLA fibers. The method includes heating to thermally bond at least a portion of the individualized bast fibers with at least a portion of the PLA fibers.

It is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

Other advantages and capabilities of the invention will become apparent from the following description taken in conjunction with the examples showing aspects of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and the above object as well as other objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawing wherein:

FIG. 1 is a graph of cross direction (CD) wet strength as a function of a series of wet agitation cycles according to aspects of the invention.

FIG. 2A is an image of a 100% flax nonwoven after one wet agitation cycle.

FIG. 2B is an image of a flax/viscose nonwoven after one wet agitation cycle.

FIG. 3A is an image of a flax/polylactic acid (PLA) nonwoven after wet agitation and drying according to aspects of the invention.

FIG. 3B is an image of a flax/viscose/PLA nonwoven after wet agitation and drying according to aspects of the invention.

DETAILED DESCRIPTION OF THE INVENTION

For a fuller understanding of the nature and desired objects of this invention, reference should be made to the above and following detailed description taken in connection with the accompanying figures. When reference is made to the figures, like reference numerals designate corresponding parts throughout the several figures.

The following definitions and abbreviations are to be used for the interpretation of the claims and the specification. As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” “contains” or “containing,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

Additionally, the term “exemplary” is used herein to mean “serving as an example, instance or illustration.” Any embodiment or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms “at least one” and “one or more” are understood to include any integer number greater than or equal to one, i.e. one, two, three, four, etc. The terms “a plurality” are understood to include any integer number greater than or equal to two, i.e. two, three, four, five, etc.

References in the specification to “one aspect,” “an aspect,” “an example aspect,” etc., indicate that the aspect described can include a particular feature or characteristic, but every embodiment may or may not include the particular structure or characteristic. Moreover, such phrases are not necessarily referring to the same aspect. Further, when a particular structure or characteristic is described in connection with an aspect, it is submitted that it is within the knowledge of one skilled in the art to affect such structure or characteristic in connection with other aspects whether or not explicitly described.

As used herein, the terms “about,” “substantially,” “approximately,” and variations thereof are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or ±2% of a given value.

As used herein, the term “biobased” means complying with the United States Department of Agriculture (USDA) Secretary in the Farm Security and Rural Investment Act of 2002 as being composed, in whole or in significant part, of biological products, renewable domestic agricultural materials (including plant, animal, and marine materials), forestry materials, or an intermediate feedstock. Biobased products are certified by the USDA.

As used herein, the term “plant-based fiber” means produced by and extracted from a plant as opposed to as opposed to man-made fibers formed from cellulose.

As used herein, the term “nonwoven” means a substrate or fabric having a structure of individual fibers or threads which are randomly interlaid, but not in an identifiable manner as in the case of a knitted or woven fabric.

As used herein, the term “wiper” means a dry wiper or a wet wiper that has been impregnated with a wetting solution. A wiper includes one or more plies of a nonwoven substrate, for example, one, two, three, or more plies.

Dry tensile strengths (both machine direction (MD) and cross direction (CD)) are measured with a standard Instron test device (Instron Corporation, Canton, Mass.) or other suitable elongation tensile tester. The tensile tester may be configured in various ways, for example using 3 or 1 inch wide strips of tissue or towel, conditioned in an atmosphere of 23° C.±1° C. (73.4° F.±1° F.) at 50% relative humidity for 2 hours. The tensile test is run at a crosshead speed of 12.0 inch/min. The sample is clamped into the two jaws, and the test separation of the jaws is initiated. Following sample breakage, the dry tensile strength is recorded.

Wet tensile strength measurements are performed according to the Payne Sponge Method using a Payne Sponge Wet Tensile Applicator (Research Dimensions, Neenah, Wis.). The substrates are cut into 1.0 inch wide specimens, clamped in the tensile tester, and wetted using the Payne sponge method. The wet sponge contacts the specimen so that the specimen appears wet. The tensile test is run at a crosshead speed of 12.0 inch/min. The sample is clamped into the two jaws, and the test separation of the jaws is initiated. Following sample breakage, the wet tensile strength is recorded.

Turning now to a description of technologies that are more specifically relevant to aspects of the present invention, as mentioned above, there is a need for methods to form a stronger, biobased nonwoven substrate that can withstand mechanical agitation, during for example, washing/laundering, while still maintaining the USDA biobased certification. While substrate strength comes from inter-fiber friction amongst entangled fibers, wet agitation, such as during washing in a washing machine or dishwasher, and/or drying can cause the fibers to disentangle and the substrate to fall apart.

Adding a thermal bonding component to fuse the fibers together and impart strength to the nonwoven substrate will allow the fibers to sufficiently maintain inter fiber bonding during wet agitation and/or drying processes. However, nonwoven substrates that use conventional thermal bonding fibers such as polyethylene terephthalate (PET) fibers or polyphenylene ether (PPE) fibers for example, will not maintain the BPI® Compostable Products certification nor be USDA certified as a biobased product.

Accordingly described herein, according to aspects of the present invention, are nonwoven fabrics and methods of making nonwoven fabrics that incorporate a biobased thermal bonding component that allows the fibers to sufficiently maintain inter fiber bonds during wet agitation and drying (or heating) processes. The biobased thermal bonding fibers are 100% biobased and certified by the USDA. The biobased thermal bonding fibers include polylactic acid (PLA) according to some aspects of the invention. The biobased fibers thermal bonding fibers are completely biodegradable in approved composting facilities. The biobased thermal bonding fibers are incorporated into a biobased nonwoven fabric, which is thermally bonded. The resulting nonwoven fabrics are dry wipers according to some aspects of the present invention. The nonwoven fabrics are also wet wipers impregnated with a wetting solution according to other aspects of the present invention. The nonwoven fabrics described herein are thermally bonded to provide a strong, 100% biobased product that can withstand wet agitation and drying processes, yet maintain USDA certification. The thermally bonded biobased nonwoven fabrics and wipers have improved wet durability, compared to non-thermally bonded biobased products, and are a USDA certified product that can be used in a variety of cleaning and maintenance applications. The nonwoven fabrics and wipers are biodegradable according to ASTM International D6400 or D6868 standard tests.

Turning now to a detailed description of aspects of the present invention, a nonwoven fabric is 100% biobased. According to some aspects, the nonwoven fabric includes bast fibers, which are plant-based fibers. The bast fiber is a flax fiber, a hemp fiber, a jute fiber, a ramie fiber, a nettle fiber, a Spanish broom fiber, a kenaf plant fiber, or any combination thereof. In an exemplary aspect, the bast fibers are flax fibers.

The amount of bast fibers incorporated into the nonwoven fabric is tailored, depending on the nonwoven fabric application. According to one or more aspects, the nonwoven fabric includes a majority (more than 50 weight % (wt. %) bast fibers. In some aspects, the bast fibers are present in a range between about 60 wt. % to about 92 wt. % based on the total weight of the nonwoven fabric. In one aspect, the bast fibers of the nonwoven fabric are present in a range between about 70 wt. % to about 80 wt. % based on the total weight of the nonwoven fabric. In another aspect, the bast fibers of the nonwoven fabric are present in a range between about 70 wt. % to about 90 wt. % based on the total weight of the nonwoven fabric. In other aspects, the amount of bast fibers in the nonwoven fabric is about or in any range between about 50, 55, 60, 65, 70, 75, 80, 85, 90, and 92 wt. % based on the total weight of the nonwoven fabric.

In one or more aspects, the bast fibers are relatively long, having a mean length of about 25 mm (1 inch) to about 150 mm (6 inches) in some aspects. In other aspects, the bast fibers have a mean length in a range from about 25 mm (1 inch) to about 50 mm (2 inches). In other aspects, the bast fibers have a mean length of at least 6 mm. In some aspects, the bast fibers have a mean length of about 6 mm to about 55 mm. Yet, in other aspects, the bast fibers have a mean length about or in any range from about 6, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, or 150 mm.

The bast fibers of the nonwoven fabric are individualized bast fibers. Individualized bast fibers utilized in this invention are typically straight and are substantially pectin-free according to one or more aspects. In contrast, conventional “individualized” bast fibers, however, may be only subjected to mechanical individualization, not chemical individualization required to substantially remove pectin content.

Naturally occurring bundled bast fibers are chemically treated to remove the pectin holding the bundles together and to separate the naturally occurring fibers into individual bast fibers. Pectin acts as natural glue which holds the individual bast fibers in the bundle. Naturally occurring bundled bast fibers first are chemically treated to substantially remove pectin and form substantially pectin-free, individualized bast fibers. Enzymatic treatment is a non-limiting example of a chemical treatment that can be used to substantially remove pectin. PCT International Publication No. WO 2007/140578, which is incorporated herein in its entirety by reference, describes a pectin removal technology which produces individualized hemp and flax fiber for application in the woven textile industry. Although individualized bast fiber is substantially straight, it has fineness similar to cotton. The process to remove pectin described in WO 2007/140578 can be employed with the present invention.

The individualized bast fibers are substantially pectin-free. In one aspect of the present invention, individualized bast fibers have less than 10% by weight of the pectin content of the naturally occurring fibers from which the substantially pectin-free fibers are derived. In another aspect, individualized bast fibers have less than 15% by weight of the pectin content of the naturally occurring fibers from which the substantially pectin-free fibers are derived. Still, in another aspect, individualized bast fibers have less than 20% by weight of the pectin content of the naturally occurring fibers from which the substantially pectin-free fibers are derived. Still, in another aspect, individualized bast fibers have less than 0.1% by weight, less than 0.15% by weight, or less than 0.20% by weight, of the pectin content of the naturally occurring fibers from which the substantially pectin-free fibers are derived.

In addition to individualized bast fibers, the nonwoven fabric includes polylactic acid (PLA) fibers, which are also plant-based fibers. The PLA fibers are 100% biobased and certified by the USDA. The PLA fibers are derived from natural and sustainable raw materials, for example, corn plants and beet plants. In an exemplary aspect of the invention, suitable PLA fibers are commercially available from Far Easter New Century Corporation, Taipei, Taiwan.

The PLA fibers function as the thermal bonding component in the nonwoven fabric, which allows the nonwoven fabric to be thermally bonded. At least a portion of the PLA fibers are thermally bonded to at least a portion of the individualized bast fibers in the nonwoven fabric. When other fibers are included in the nonwoven fabric, such as cellulose fibers (e.g., regenerated cellulose fibers), at least a portion of the PLA fibers also will be thermally bonded to the cellulose fibers. According to some aspects, the PLA fibers have a melting point of about 120° C. to about 170° C. In other aspects, the PLA fibers have a melting point of about 130° C. to about 135° C. In an exemplary aspect, the PLA fibers have a melting point of about 130° C. Yet, in some aspects, the PLA fibers have a melting point about or in any range from about 120, 130, 135, 140, 145, 150, 155, 160, 165, and 170° C.

In some aspects, the PLA fibers are bi-component fibers and/or have more than one melting point, or a range of melting points. In one aspect, the PLA fibers include a low melting point sheath and higher melting PLA core.

In addition to the melting point, the denier and mean length of the PLA fibers make them favorable for use as a thermal bonding component in the nonwoven fabric. The PLA fibers, according to aspects of the invention, have a mean fiber length of about 45 mm to about 55 mm. In other aspects, the PLA fibers have a mean length of about 3 mm to about 55 mm. In some aspects, the PLA fibers have a mean length of about 3 mm (⅛ inch) to about 25 mm (1 inch). Yet, in one or more aspects, the PLA fibers have a mean length about or in any range from about 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, and 55 mm. The denier of the PLA fibers is about 3.6 to about 4.4 in some aspects. In other aspects, the denier of the PLA fibers is about 1.5 to about 4.4.

The amount of PLA fibers incorporated into the nonwoven fabric is tailored, depending on the nonwoven fabric application. In some aspects, the PLA fibers are present in a range between about 8 wt. % to about 30 wt. % based on the total weight of the nonwoven fabric. In one aspect, the PLA fibers of the nonwoven fabric are present in a range between about 15 wt. % to about 25 wt. % based on the total weight of the nonwoven fabric. In another aspect, the PLA fibers of the nonwoven fabric are present in a range between about 8 wt. % to about 15 wt. % based on the total weight of the nonwoven fabric. In other aspects, the amount of PLA fibers in the nonwoven fabric is about or in any range between about 8, 10, 12, 15, 17, 20, 22, 25, 27, and 30 wt. % based on the total weight of the nonwoven fabric.

In some aspects, the nonwoven fabric includes only bast fibers and PLA fibers. In other aspects, the nonwoven fabric includes bast fibers, PLA fibers, and cellulose fibers, which can be natural cellulose fibers or regenerated/reconstituted cellulose fibers. Regenerated/reconstituted cellulose fibers are man-made fibers formed from cellulose. Examples of regenerated cellulose include, but are not limited to, rayon, lyocell, (e.g., TENCEL®), Viscose®, or any combination thereof. TENCEL® and Viscose® are commercially available from Lenzing Aktiengesellschaft, Lenzing, Austria. Wood pulp fibers, or papermaking fibers (such as softwood fibers or hardwood fibers), are examples of natural cellulose fibers. The cellulose fibers can be chemically pulped or mechanically pulped, bleached or unbleached, virgin or recycled, high yield or low yield, and the like.

When included in the nonwoven fabric, the cellulose fibers are present in a range between about 1 wt. % and about 40 wt. % based on the total weight of the nonwoven fabric. In one aspect, the cellulose fibers of the nonwoven fabric are present in a range between about 5 wt. % to about 30 wt. % based on the total weight of the nonwoven fabric. In another aspect, the cellulose fibers of the nonwoven fabric are present in a range between about 10 wt. % to about 20 wt. % based on the total weight of the nonwoven fabric. In other aspects, the amount of cellulose fibers in the nonwoven fabric is about or in any range between about 1, 5, 10, 15, 20, 25, 30, 35, and 40 wt. % based on the total weight of the nonwoven fabric.

In addition to the above mentioned fibers (bast fibers, PLA fibers, and cellulose fibers), the nonwoven fabric includes any other biobased fibers according to some embodiments.

To form the nonwoven fabric, the fibers are combined and formed into a fiber web. The web includes individualized bast fibers and PLA fibers according to some aspects. According to other aspects, the web includes individualized bast fibers, PLA fibers, and cellulose fibers, such as regenerated cellulose fibers.

Air-laying processes are used to form the fiber web according to some aspects of the invention. Dry-laying processes are used to form the fiber web according to other aspects of the invention. In the air-laying processes (also called air-laid processes or air-forming processes), only airflow, gravity, and centrifugal force are used to deposit a stream of fibers onto a moving forming wire. Air-laid processes are described in, for example, PCT International Publication No. WO 03/099886 and U.S. Pat. Nos. 4,014,635 and 4,640,810, all of which are respectively incorporated herein in their entirety by reference.

According to an exemplary aspect of the invention, carding, an air-laid process, is used to form the fiber web. The mechanical process of carding is described in, for example, U.S. Pat. No. 797,749, which is incorporated herein in its entirety by reference. The carding process includes an airstream component to randomize the orientation of the staple fibers when they are collected on the forming wire.

In addition to air-laying processes, the fiber webs are formed by classical, wet-laid papermaking processes according to some aspects of the invention. In exemplary aspects, the fiber webs are made using any one of various, commonly practiced dispersant techniques to disperse a uniform furnish of fibers onto a foraminous screen of a conventional papermaking machine. U.S. Pat. Nos. 4,081,319 and 4,200,488, both of which are incorporated herein in their entirety by reference, disclose exemplary wet-laying methods which may be used in the present invention.

After forming a fiber web, the fibers are then subjected to entanglement (such as hydroentanglement or needlepunch, for example) to produce a nonwoven fabric in which the fibers are interlaced (entangled) with one another. According to aspects of the invention, hydroentanglement (hydroentangling) is used to form the nonwoven fabric. According to some aspects of the invention, needlepunch is used to form the nonwoven fabric.

Hydroentanglement processes are known in the art. Non-limiting examples of the hydroentangling process are described in Canadian Patent No. 841,938, U.S. Pat. Nos. 3,485,706, and 5,958,186. U.S. Pat. Nos. 3,485,706 and 5,958,186, respectively, are incorporated herein in their entirety. Hydroentangling involves forming a dry-laid fiber web (or webs) and thereafter entangling the fibers by employing very fine water jets under high pressure. For example, a plurality of rows of waterjets is directed towards the fiber web which is disposed on a moving support, such as a wire (mesh). The level of bonding is determined by the energy imparted to the web by the hydroentangling jets. The hydroentangling energy necessary to entangle the fibers depends on many factors, including the desired level of bonding, basis weights, specific fibers utilized, and other factors. The entangled web is then dried.

Entangling by needle punch refers to a bonding process in which the subsequent material uses oscillating barbed needles to mechanically entangle and interlock the fibers of a web.

The method includes entangling the individualized bast fibers and PLA fibers, and optionally, cellulose fibers and/or other biobased fibers when included.

After forming the entangled fiber web, the entangled fiber web is heated to bond the entangled fiber web. The heating process is thermal bonding according to an exemplary aspect. The heating process is through air bonding according to other aspects. Thermal bonding is also referred to as calendar bonding, point bonding, thermal point bonding, or pattern bonding, and is used to bond the entangled fiber web to form the thermally bonded nonwoven fabric. In some aspects, thermal bonding is used to incorporate a pattern into the fabric. Thermal bonding is described in PCT International Publication No. WO/2005/025865, which is incorporated herein in its entirety by reference. In thermal bonding, the entangled fiber web is bonded under pressure by heating the entangled fiber web. The web can be heated by passing through a nip of heated calendar rolls under pressure, which can be embossed with a pattern that transfers to the surface of the fiber web. The calendar rolls are heated to a temperature that is about the melting point of the PLA fibers. In some aspects, the calendar rolls are heated to a temperature of about 120° C. to about 170° C. In other aspects, the calendar rolls are heated to a temperature of about 130° C. to about 135° C. Yet, in other aspects, the calendar rolls are heated to a temperature about or in any range from about 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, and 170° C.

According to one or more aspects, the entangled fiber web is heated at a temperature of about 120 to about 170° C. In other aspects, the entangled fiber web is heated to a temperature of about 130 to about 135° C. Still yet, in other aspects, the entangled fiber web is heated to a temperature about or in any range from about 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, and 170° C.

Heating, such as thermal bonding, thermally bonds at least a portion of the PLA fibers with at least a portion of the individualized bast fibers. When other fibers are included in the entangled web, such as cellulose fibers (e.g., regenerated cellulose fibers), at least a portion of the PLA fibers are also thermally bonded to the cellulose fibers.

After heating the entangled web by thermal bonding, the nonwoven fabric is strong enough to withstand wet mechanical agitation and drying processes, making it suitable for use as a wet wiper or dry wiper in a variety of applications. The CD wet tensile strength of a nonwoven is measured according to the Payne Sponge Method, which is described above. Compared to nonwoven substrates without PLA, the thermally bonded nonwoven substrates described herein have a significantly higher CD wet tensile strength. In some aspects, the nonwoven substrate has a CD wet tensile strength of at least 1,000 grams/inch (g/in). In other aspects, the nonwoven substrate has a CD wet tensile strength of about 1,000 g/in to about 1,400 g/in. Yet, in some aspects the nonwoven substrate has a CD wet tensile strength of about 1,000 to about 1,200 g/in. Still yet, in other aspects, the nonwoven substrate has a CD wet tensile strength of at least 500 g/in. In some aspects, the nonwoven substrate has a CD wet tensile strength of about 500 to about 1,400 g/in.

The basis weight of the nonwoven substrate depends on the specific application intended. In some aspects, the basis weight of the nonwoven substrate is about 40 to about 100 grams/m² (gsm). In other aspects, the basis weight of the nonwoven substrate is about 40 to about 60 gsm.

The nonwoven fabric of the present invention can be incorporated into a variety of products. Non-limiting examples of products include wipers (or wipes), such as wet wipers, dry wipers, or impregnated wipers, which include personal care wipers, cleaning wipers, industrial wipers, and dusting wipers. Personal care wipers can be impregnated with, e.g., emollients, humectants, fragrances, and the like. Household cleaning wipers or hard surface cleaning wipers can be impregnated with, e.g., surfactants (for example, quaternary amines), peroxides, chlorine, solvents, chelating agents, antimicrobials, fragrances, and the like. Dusting wipers can be impregnated with, e.g., oils.

According to one or more aspects, the nonwoven fabric is incorporated into a launderable reusable industrial wiper, such as a launderable shop rag, or a food service towel. The thermally bonded wiper fibers are sufficiently bonded to withstand the agitation of a laundry washing machine or water-jet force of a commercial dish washer.

Non-limiting examples of wipers include baby wipes, cosmetic wipes, perinea wipes, disposable washcloths, household cleaning wipes, such as kitchen wipes, bath wipes, or hard surface wipes, disinfecting and germ removal wipes, specialty cleaning wipes, such as glass wipes, mirror wipes, leather wipes, electronics wipes, lens wipes, and polishing wipes, medical cleaning wipes, disinfecting wipes, and the like. Additional examples of products include sorbents, medical supplies, such as surgical drapes, gowns, and wound care products, personal protective products for industrial applications, such as protective coveralls, sleeve protectors, and the like, protective coverings for automotive applications, and protective coverings for marine applications. The nonwoven fabric can be incorporated into absorbent cores, liners, outer-covers, or other components of personal care articles, such as diapers (baby or adult), training pants, feminine care articles (pads and tampons) and nursing pads. Further, the nonwoven fabric can be incorporated into fluid filtration products, such air filters, water filters, and oil filters, home furnishings, such as furniture backing, thermal and acoustic insulation products, agricultural application products, landscaping application products, and geotextile application products. A variety of wetting compositions, formed from one or more of the above-described components, can be used with the wipers of the present invention.

Examples

Five sets of nonwoven substrate samples were prepared, as shown in Table 1 below. Cells 2 and 3 included flax fibers, viscose fibers, and PLA fibers. Cell 5 only included flax fibers and PLA fibers. Cells 1 and 4 were controls and did not include PLA fibers. The fibers were hydroentangled, and samples with PLA fibers were heated.

The flax fibers used had a mean length of about 6-25 mm. The viscose fibers were about 1.5 denier and about 38 mm in length. The PLA fibers were about 4.0 denier, about 50 mm in length. For cells 2 and 5, the PLA fibers had a minimum melting point of 170° C. The PLA fibers were heated to 170° C. to thermally bond them to the flax fibers. The PLA fibers in cell 3 had a minimum melting temperature of 120° C. and were heated to 120° C. to thermally bond them to the flax fibers.

TABLE 1 Sheet composition Thermal Target Bonding Basis Cell Temperature weight # Composition (° C.) (gsm) Pattern 1 Flax 75%/Viscose 25% — 55 Flat Sheet 2 Flax 75%/Viscose 17%/ 170 55 Flat Sheet PLA 8% 3 Flax 75%/Viscose 17%/ 120 55 Flat Sheet PLA 8% 4 100% Flax — 55 Flat Sheet 5 Flax 92%/PLA 8% 170 55 Flat Sheet

The hydroentangled wipers were tested for physical properties, hand feel, compostability, and washability. To assess the strength of the samples and the ability to withstand mechanical agitation, the samples were washed and dried and subjected to a series of wash cycles in a washing machine. FIG. 1 and Table 3 show the CD wet strength (g/in) of the samples before washing, and up to 5 cycles of washing. The samples were dried in a residential clothes dryer between washing cycles.

As shown in FIG. 1, cells 1 and 4 (flax/viscose and 100% flax) did not survive the first cycle of washing to be tested for strength. FIG. 2A shows an image of the sheet from cell 4 (100% flax) after one cycle of washing. FIG. 2B shows an image of the sheet from cell 1 (flax/viscose) after one cycle of washing.

Cells 2, 3, and 5 maintained sufficient CD wet strength to survive 5 cycles of washing and drying in a washing machine. FIG. 3A shows an image of the sheet from cell 5 (flax/PLA) after five cycles of washing and drying. FIG. 3B shows an image of the sheet from cell 3 (flax/viscose/PLA) after five cycles of washing and drying.

TABLE 3 CD Wet Strength CD Wet Strength Cell # Before Wash 1 Cycle 2 Cycles 3 Cycles 4 Cycles 5 Cycles 1 719 — — — — — 2 1,242 829 950 838 227 798 3 1,301 629 652 736 596 562 4 647 — — — — — 5 415 440 466 485 321 422

Table 4 below shows % PLA after extracting the hydroentangled substrates with chloroform.

TABLE 4 % PLA Cell # Composition % PLA 1 Flax 75%/Viscose 25% 0.3% 2.1 Flax 75%/Viscose 17%/ 18.68% PLA 8% (170° C.) 2.2 Flax 75%/Viscose 17%/ 17.16% PLA 8% (170° C.)/Heated 3.1 Flax 75%/Viscose 17%/ 16.60% PLA 8% (120° C.) 3.2 Flax 75%/Viscose 17%/ 15.60% PLA 8% (120° C.)/Heated 4 100% Flax 0.44% 5.1 Flax 92%/PLA 8% 12.03% 5.2 Flax 92%/PLA 8%/Heated 11.43% PLA Fibers 100% PLA 101.67%

Table 5 shows physical properties of the hydroentangled substrates, including wet and dry tensile strengths and wet and dry ball burst measurements. Ball burst measurements were performed to assess the puncture strength of the substrates, which was indicative of thermal bonding in the z-direction. To perform the measurements, a ball burst fixture was used from MTS Systems Corporation, Stoughton, Mass. An Instron tensile tester also was used from Instron Corporation, Canton, Mass. Dry and wet ball burst measurements were performed by following INDA Wiper Ball Burst Test Method WSP 110.5 R4(12). The method measures the out-of-plane force to break a nonwoven sample using a 1-inch diameter polished steel ball probe. The probe is attached to a load cell in an Instron tensile test apparatus. The nonwoven sample is clamped securely in a horizontal orientation below the probe. During the test, the probe moves vertically downward to contact and eventually penetrate the nonwoven sheet. The force to break the sample is reported. Sheets may be tested dry or wet.

TABLE 5 Physical Properties Ball Brst Ball Brst Dry Wet Basis Caliper Tensile Tensile Wet Tens Wet Tens Wipers- Wipers- Weight mm/1 1 × 4″ MD 1 × 4″ CD 1 × 4-MD 1 × 4-CD Ld Ld Cell # g/m² sht g/1 in g/1 in g/1 in g/1 in lb lb 1 53.50 0.569 1,474.97 898.84 1,395.45 718.90 9.8 8.5 2 58.04 0.619 1,812.93 1,159.23 1,907.15 1,242.00 8.2 9.3 3 52.27 0.535 1,989.98 1,069.79 2,066.89 1,301.35 11.4 11.7 4 56.22 0.523 688.11 335.72 775.16 414.61 3.5 10.9 5 60.84 0.617 1,063.49 669.61 1,146.60 646.97 4.8 8.5

With respect to the above description, it is to be realized that the optimum proportional relationships for the parts of the invention, to include variations in components, concentration, shape, form, function, and manner of manufacture, and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the specification are intended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, various modifications may be made of the invention without departing from the scope thereof, and it is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and which are set forth in the appended claims. 

1. A nonwoven fabric, comprising: an entangled web of individualized bast fibers and polylactic acid (PLA) fibers; wherein at least a portion of the bast fibers and a portion of the PLA fibers are thermally bonded together.
 2. The nonwoven fabric of claim 1, wherein the PLA fibers are present in an amount in a range from about 8 to about 30 weight % (wt. %).
 3. (canceled)
 4. (canceled)
 5. The nonwoven fabric of claim 1, wherein the individualized bast fibers have a mean length of about 6 to about 55 millimeters (mm).
 6. (canceled)
 7. (canceled)
 8. (canceled)
 9. (canceled)
 10. (canceled)
 11. The nonwoven fabric of claim 1, wherein the PLA fibers have a melting point of about 120° C. to about 170° C.
 12. (canceled)
 13. (canceled)
 14. (canceled)
 15. The nonwoven fabric of claim 1, wherein the individualized bast fibers are substantially pectin-free.
 16. (canceled)
 17. A nonwoven fabric, comprising: an entangled web of individualized bast fibers, polylactic acid (PLA) fibers, and cellulose fibers; wherein at least a portion of the PLA fibers are thermally bonded to the bast fibers and at least a portion of the PLA fibers are thermally bonded to the cellulose fibers.
 18. The nonwoven fabric of claim 17, wherein the cellulose fibers are regenerated cellulose fibers.
 19. The nonwoven fabric of claim 17, wherein the PLA fibers are present in an amount in a range from about 8 to about 30 weight % (wt. %).
 20. (canceled)
 21. (canceled)
 22. (canceled)
 23. (canceled)
 24. The nonwoven fabric of claim 17, wherein the individualized bast fibers have a mean length of about 6 to about 55 millimeters (mm).
 25. (canceled)
 26. (canceled)
 27. The nonwoven fabric of claim 17, wherein the nonwoven fabric is biodegradable according to ASTM International D6400 or D6868 standard tests.
 28. (canceled)
 29. (canceled)
 30. The nonwoven fabric of claim 17, wherein the PLA fibers have a melting point of about 120° C. to about 170° C.
 31. (canceled)
 32. (canceled)
 33. (canceled)
 34. The nonwoven fabric of claim 17, wherein the individualized bast fibers are substantially pectin-free.
 35. (canceled)
 36. A method of making a nonwoven fabric, the method comprising: forming a web comprising individualized bast fibers and polylactic acid (PLA) fibers; entangling the individualized bast fibers and the PLA fibers; and heating to thermally bond at least a portion of the individualized bast fibers with at least a portion of the PLA fibers.
 37. The method of claim 36, wherein the web further comprises cellulose fibers.
 38. The method of claim 37, wherein the cellulose fibers are regenerated cellulose fibers.
 39. The method of claim 36, wherein heating is performed at a temperature of about 120° C. to about 170° C.
 40. The method of claim 36, wherein the PLA fibers are present in an amount in a range from about 8 to about 30 weight % (wt. %).
 41. (canceled)
 42. (canceled)
 43. The method of claim 36, wherein the individualized bast fibers have a mean length of about 6 to about 55 millimeters (mm).
 44. (canceled)
 45. The method of claim 36, wherein the PLA fibers have a melting point of about 120° C. to about 170° C.
 46. (canceled)
 47. The method of claim 36, wherein the individualized bast fibers are substantially pectin-free.
 48. (canceled)
 49. (canceled)
 50. (canceled)
 51. (canceled) 